This type of spreadable instrument for endoscopic interventions is known in various embodiments. One preferred application is the configuration of such an instrument as a laryngoscope. Laryngoscopes are used particularly for direct instrumental inspection of the throat as well as for endolaryngeal surgical interventions. Owing to the adjustability of the spatula blades, it is possible to vary the free lumen that is formed by the spatula blades turned toward one another to form an essentially semicircular cross-section, in such a way that the laryngoscope is introduced in a closed starting position with a minimal lumen into the mouth and pharynx area of the intubated, anesthetized patient and that only afterward is the lumen enlarged by parallel and/or angular displacement of the spatula blades to one another so that appropriate medical instruments can be inserted into the laryngoscope.
Additional fields of application for such spreadable medical instruments include, in particular, neck surgery and the use of the mediastinoscope.
A generic spreadable medical instrument is described, for instance, in U.S. Pat. No. 5,938,591. This patent teaches a laryngoscope with two spatula blades which can be adjusted parallel and at angles to one another by means of a ratchet mechanism for each. These ratchet mechanisms are configured in such a way that, upon activation, they ratchet the blades in a pre-established ratchet position to one another. In addition to the protruding construction of the ratchet mechanism that stands far from the handle, this construction from the prior art has the disadvantage that the blades can be displaced with respect to one another only in the pre-established lock steps, which can in practice cause a position of the blades that is too narrow or else too wide for the current use.
Another instrument configured as a laryngoscope, for instance, is described in DE 199.54.442.A1. In this laryngoscope from prior art, the handle and the placement elements of the adjustment mechanism for adjusting the spatula blades are configured in such a way that the operator must use both hands for the purpose, which is not particularly advantageous in laryngoscopy since the laryngoscope, after positioning, must be securely fixed to the patient or the operating table.
However, for use in neck surgery, for instance, an endoscope with spatulas is inserted into an incision in the back of the neck and the spatulas then moves the tissue, stretching it apart until sufficient access to the operating area is provided. For this operating technique, as well as for use as a mediastinoscope, it is essential that the operator has one hand free for operating additional medical instruments.